Electric furnace



|. RENNERF ELT.

ELECTRIC FURNACE.

PLICATION FILED AUG 10 I I921- 43 424 Patented Oct. 10, 1922.

Patented Oct. 10,

UNITED STATES IVAR mmmrnm, or DJ'UBSHOLI, swnnnn.

ELECTRIC FURNACE.

Application filed August 10, 1921. Serial in. 491,170.

(GBAHTEIi UNDER. THE PROVISIONS OF THE ACT 01' men 3, 1921, 41 STAT. L, 1313.)

To all whom it may concern:

Be it known that I, IVAR RENNERFELT, a citizen of the Kingdom of Sweden, and resident of Djursholm, in the county of Stock- 'holms Lan and Kingdom of Sweden, have invented certain new and useful Improvements in Electric Furnaces, (for which I have filed applications for Letters Patents in Sweden Aug. 23rd, 1918, Patent No. 47,450; in Norway June 25th,,1920', Patent No. 32,500), of which the following is a specification.

My invention relates to' improvements in electric furnaces, which are heated by arcs from one or more electrodes projecting into a furnace room from above. The objects of my improvement are, first, to provide an electric furnace for uniformly and efiiciently heating a number of articles; second, to arrange the heating'elements of the furnace so as to facilitate the control of the rate of heating and the transformation of electric energy into heat. A third object is to suitably combine electrodes with a powdered resistance in order to improve the starting and running conditions of the furnace.

I attain these objects by building a furnace as. illustrated in the accompanying drawing in which Fig. 1 is a vertical section of the furnace and Fig. 2 a horizontal section at ae-m in Fig. 1. Similar letters refer to similar parts in both views. I

A quantity 1 of powdered carbon (graphite) affords contacts for electric arcs 2 generated by one or more electrodes 3, projecting from above through a cover 4.

A ring-shaped rotatable hearth 5 surrounds the centrally located source of heating.

Balls or rollers 6 support the hearth, which may be rotated by means of a gearwheel 7 meshing with a gear 8 on the lower side of the hearth.

On the side of the furnace wall 9 are doors 10, closir1 1; op1 snings 11, whichpermitpladv ing objects to be heated on t e rotatable hearth.

The number of electrodes is determined by the size of the furnace and the nature of the current employed. In the central part supporting the powder a contact 12 may be provided, if the conditions for transforming the electric energy into heat should so demand.

By properly modifying the interior surface 0 the roof the heat rays from the arcs may be reflected downwards onto the objects of the rotatable hearth. The carbon powder underneath the electrodes should be as pure as possible so as to avoid formation of slag and ashes. An opening may be provided in the cover for refilling of the carbon powder on the central hearth.

A furnace as described may be used for heating objects forforging or heat treating purposes, for melting in crucibles, which may be placed on the hearth and for burning ceramic objects of porcelain or clay.

Having now fully described my invention I claim:

1. In an electric furnace the combination of a centrally located hearth, supporting a quantity of carbonaceous powder, an electrode rojecting downwards from the roof into 0 ose proximity, of the powder and a ringshaped hearth, surrounding the central hearth and adapted to be rotated around said hearth.

2. In an electric furnace the combination of a centrally located hearth, supporting a quantityof carbonaceous powder, a bottom contact entering the central hearth, an electrode projecting downwards from the'roof into close proximity to the carbon powder and a rotatable ringshaped hearth surrounding the central hearth.

Signed at Stockholm, in the county of Stockholms Lan and State of Sweden. this 26th day of July A. D. 1921.

IVAR RENNERFELT.

-.Witnesses:

W. C. Hlxsol. S. Swanson. 

